I would like them to be visible in IE8 (XP) IE9 IE10 Chrome and Firefox, and to be selected from a playlist

Looks like using the video tag (html5) is a good solution: natively works in FF, Chrome, IE10,... and the flashback fallback for in IE8

I am stumbling again and again regarding the flashplayer fallback in IE8

I have the clips in 3 formats each (ogg for FF, mp4 for Chrome, flv for IE8). I use Miro for conversion to ogg, Super for conversion to mp4 and flv and, finally, use FLV Injector (or something like that) to add proper metadata to the resulting flv.

Using flv-player.net player I got to see everything, but in IE8 the player runs once,.... and then the picture screen gets black forever. And no answer from flv-player

May I get some advice, please? Use or not video html5? What (free) swf player?

By all means, use HTML. But for people who have older browsers, YouTube is an acceptable option, and the player is not only familiar to people, but also more professionally designed than most free players.

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Praise be to the Lord God for the ability to learn, the capability to analyze, and the time to help users on this forum.